Avian maternal response to chick distress

The extent to which an animal is affected by the pain or distress of a conspecific will depend on its capacity for empathy. Empathy most likely evolved to facilitate parental care, so the current study assessed whether birds responded to an aversive stimulus directed at their chicks. Domestic hens were exposed to two replicates of the following conditions in a counterbalanced order: Control (C; hen and chicks undisturbed), Air Puff to Chicks (APC; air puff directed at chicks at 30 second intervals), Air Puff to Hen (APH; air puff directed at hen at 30 second intervals) and Control with Noise (CN; noise of air puff at 30 second intervals). During each test, the hens’ behaviour and physiology were measured throughout a 10-minute pre-treatment and a 10-minute treatment period. Hens responded to APH and APC treatments with increased alertness, decreased preening behaviour and a reduction in eye temperature. No such changes occurred during any control period. Increased heart rate and maternal vocalisation occurred exclusively during the APC treatment, even though chicks produced few distress vocalisations. The pronounced and specific reaction observed indicates that adult female birds possess at least one of the essential underpinning attributes of empathy.